Most people work out with a goal in mind. They have a certain weight they want to get down to, a certain pants size they want to wear. Whatever it is their goal is, they can point at it and say "This is what I want, this is how close I am."

What about gaining weight and muscle, can that be given a specific goal? Is there any magic motivation trick to make post-workout soreness worth it? What have you guys done to get yourself up and motivated?